Millions of species populate Earth. The vast majority gain energy to support their metabolism either directly from the sun, in the case of plants, or, in the case of animals and microbes, from other organisms through feeding on plants, predation, parasitism, or decomposition. In the pursuit of life and through their capacity to reproduce, organisms use energy, water, and nutrients. Organisms interact with one another in many ways, including competitive, predatory, parasitic, and facilitative ways, such as pollination, seed dispersal, and the provision of habitat. These fundamental linkages among organisms and their physical and biological environment constitute an interacting and ever-changing system that is known as an ecosystem. Humans are a component of these ecosystems. Indeed, in many regions they are the dominant organism. Whether dominant or not, however, humans depend on ecosystem properties and on the network of interactions among organisms and within and among ecosystems for sustenance, just like all other species.
Ecosystem services are the benefits people obtain from ecosystems. This definition is derived from two other commonly referenced and representative definitions:
Ecosystem services are the conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfill human life. They maintain biodiversity and the production of ecosystem goods, such as seafood, forage timber, biomass fuels, natural fiber, and many pharmaceuticals, industrial products, and their precursors (Daily 1997b:3).
Ecosystem goods (such as food) and services (such as waste assimilation) represent the benefits human populations derive, directly or indirectly, from ecosystem functions (Costanza et al. 1997:253).
The Millennium Ecosystem Assessment (MA) definition follows Costanza and his colleagues in including both natural and human-modified ecosystems as sources of ecosystem services, and it follows Daily in using the term “services” to encompass both the tangible and the intangible benefits humans obtain from ecosystems, which are sometimes separated into “goods” and “services” respectively. Like the term ecosystem itself, the concept of ecosystem services is relatively recent—it was first used in the late 1960s (e.g., King 1966; Helliwell 1969). Research on ecosystem services has grown dramatically within the last decade (e.g., Costanza et al. 1997; Daily 1997a; Daily et al. 2000; de Groot et al. 2002).
Types of Ecosystem Services
Ecosystem services have been categorized in a number of different ways, including by:
· functional groupings, such as regulation, carrier, habitat, production, and information services (Lobo 2001; de Groot et al. 2002);
· organizational groupings, such as services that are associated with certain species, that regulate some exogenous input, or that are related to the organization of biotic entities (Norberg 1999); and
· descriptive groupings, such as renewable resource goods, non-renewable resource goods, physical structure services, biotic services, biogeochemical services, information services, and social and cultural services (Moberg and Folke 1999).
Millennium Ecosystem Assessment approach classify ecosystem services along functional
lines using categories of provisioning, regulating, cultural, and supporting services.
These are the products obtained from ecosystems, including:
· Food and fiber. This includes the vast range of food products derived from plants, animals, and microbes, as well as materials such as wood, jute, hemp, silk, and many other products derived from ecosystems.
· Fuel. Wood, dung, and other biological materials serve as sources of energy.
· Genetic resources. This includes the genes and genetic information used for animal and plant breeding and biotechnology.
· Biochemicals, natural medicines, and pharmaceuticals. Many medicines, biocides, food additives such as alginates, and biological materials are derived from ecosystems.
· Ornamental resources. Animal products, such as skins and shells, and flowers are used as ornaments, although the value of these resources is often culturally determined. This is an example of linkages between the categories of ecosystem services.
· Fresh water. Fresh water is another example of linkages between categories— in this case, between provisioning and regulating services.
These are the benefits obtained from the regulation of ecosystem processes, including:
· Air quality maintenance. Ecosystems both contribute chemicals to and extract chemicals from the atmosphere, influencing many aspects of air quality.
· Climate regulation. Ecosystems influence climate both locally and globally. For example, at a local scale, changes in land cover can affect both temperature and precipitation. At the global scale, ecosystems play an important role in climate by either sequestering or emitting greenhouse gases.
· Water regulation. The timing and magnitude of runoff, flooding, and aquifer recharge can be strongly influenced by changes in land cover, including, in particular, alterations that change the water storage potential of the system, such as the conversion of wetlands or the replacement of forests with croplands or croplands with urban areas.
· Erosion control. Vegetative cover plays an important role in soil retention and the prevention of landslides.
· Water purification and waste treatment. Ecosystems can be a source of impurities in fresh water but also can help to filter out and decompose organic wastes introduced into inland waters and coastal and marine ecosystems.
· Regulation of human diseases. Changes in ecosystems can directly change the abundance of human pathogens, such as cholera, and can alter the abundance of disease vectors, such as mosquitoes.
· Biological control. Ecosystem changes affect the prevalence of crop and livestock pests and diseases.
· Pollination. Ecosystem changes affect the distribution, abundance, and effectiveness of pollinators.
· Storm protection. The presence of coastal ecosystems such as mangroves and coral reefs can dramatically reduce the damage caused by hurricanes or large waves.
Ecosystem Services in a Snapshot
These are the nonmaterial benefits people obtain from ecosystems through spiritual enrichment, cognitive development, reflection, recreation, and aesthetic experiences, including:
· Cultural diversity. The diversity of ecosystems is one factor influencing the diversity of cultures.
· Spiritual and religious values. Many religions attach spiritual and religious values to ecosystems or their components.
· Knowledge systems (traditional and formal). Ecosystems influence the types of knowledge systems developed by different cultures.
· Educational values. Ecosystems and their components and processes provide the basis for both formal and informal education in many societies.
· Inspiration. Ecosystems provide a rich source of inspiration for art, folklore,national symbols, architecture, and advertising.
· Aesthetic values. Many people find beauty or aesthetic value in variousaspects of ecosystems, as reflected in the support for parks, “scenic drives,” and the selection of housing locations.
· Social relations. Ecosystems influence the types of social relations that are established in particular cultures. Fishing societies, for example, differ in many respects in their social relations from nomadic herding or agricultural societies.
· Sense of place. Many people value the “sense of place” that is associated with recognized features of their environment, including aspects of the ecosystem.
· Cultural heritage values. Many societies place high value on the maintenance of either historically important landscapes (“cultural landscapes”) or culturally significant species.
· Recreation and ecotourism. People often choose where to spend their leisure time based in part on the characteristics of the natural or cultivated landscapes in a particular area.
Supporting services are those that are necessary for the production of all other ecosystem services. They differ from provisioning, regulating, and cultural services in that their impacts on people are either indirect or occur over a very long time, whereas changes in the other categories have relatively direct and short-term impacts on people. For example, humans do not directly use soil formation services, although changes in this would indirectly affect people through the impact on the provisioning service of food production.
Substitutes are available for some ecosystem services, although often the cost of a technological substitution will be high and it may not replace all the services lost. For example, water treatment plants can now substitute for ecosystems in providing clean drinking water, although this may be expensive and will not overcome the impacts of water pollution on other components of the ecosystem and the services they provide. Another outcome of substitution is that often the individuals gaining the benefits are not those who originally benefited from the ecosystem services. Therefore, a full assessment of ecosystems and their services must consider:
· information on the cost of a substitute,
· the opportunity cost of maintaining the service,
· cross-service costs and impacts, and
· the distributional impacts of any substitution.
BY - Dipankar Chatterjee; Asst. Professor, Faculty of IRTDM, RKMVERI, Ranchi